Just one in four 999 calls received by police last year was classed as an emergency, figures showed today.

This fell to less than one in five in Britain's biggest force, the Metropolitan Police, where less than 400,000 of the two million 999 calls needed an emergency response, figures released to the Press Association under the Freedom of Information Act showed.

The figures come as the Met disclosed some of the spurious 999 calls it received last Christmas Day.

One was from a woman claiming someone was in her house, and she knew this because she had invented an X-ray machine.

One man claimed to be David Cameron calling from 10 Downing Street, while another demanded to speak to the head of the Egyptian order.

Another simply said, "I love you with all my heart darling", before hanging up.

In 2010/11, an average of one in four 999 calls needed an emergency response, figures from 31 of the 43 forces in England and Wales showed.

Overall, some 7.5 million 999 calls were received by the forces which responded to the FoI request, but less than 1.9 million of these were emergencies.

In Suffolk, just 3,227 of the 30,291 999 calls were an emergency - just one in 10 - the figures showed.

But in Derbyshire, almost two-thirds of 999 calls were an emergency.

Chief Superintendent Jim Read, from the Met's central communications command, said: "Deliberate misuse of the 999 emergency system presents a very real risk to our ability to effectively respond to genuine emergencies."

He also urged callers with inquiries about stolen cars, damaged property, drug dealing or a minor traffic accident to call the non-emergency 101 number instead.